Multi-nozzle micro-nano 3D printing device and method based on second electrode auxiliary electric field driving

Abstract

The invention relates to the technical field of 3D printing, in particular to a multi-nozzle micro-nano 3D printing device and method based on second electrode auxiliary electric field driving. The injection process is controlled through the first voltage, and the second electrode voltage is used for controlling deflection of the jet flow. Because the voltage of the second electrode is adjustable and the jet flow surface is provided with positive charges, the deflection of the conical jet flow can be accurately controlled by adjusting the voltage under the interaction of the electric field.

Description

Technical Field

[0001] This application relates to the field of 3D printing technology, and in particular to a device and method for multi-nozzle micro / nano 3D printing driven by a second electrode-assisted electric field. Background Technology

[0002] Micro-nano additive manufacturing is a novel micro-nano fabrication technology based on the principles of additive manufacturing to create micro- and nano-structures or functional objects. Compared with traditional manufacturing methods, it has advantages such as low cost, simple structure, a wide variety of usable materials, no need for masks or molds, and direct molding. It is considered one of the top ten disruptive technologies of the 21st century and has achieved rapid development over the past decade. Currently, representative processes in micro-nano additive manufacturing mainly include micro-stereolithography, two-photon polymerization, aerosol jet printing, micro-laser sintering, and electrohydraulic inkjet printing. Micro-stereolithography can achieve a maximum resolution of 0.6 μm, but its printing materials are mainly photosensitive resins. Although theoretically non-photosensitive materials such as ceramics and metals can be used, the molding of these materials requires additional processes such as sintering and debinding, which significantly increases the complexity of the process and the production cost. Two-photon polymerization has achieved the fabrication of arbitrarily complex three-dimensional structures with a minimum molding size of 160 nm, but this technology has low efficiency, expensive equipment, and small molding size. Its printing materials are limited to photosensitive materials, which seriously restricts its application expansion in fields such as biomedicine and flexible electronics. Aerosol jetting has achieved high-precision circuit printing of 10 μm with a printing material viscosity of 1000 mPa·s and has the ability to print on both curved and uneven surfaces. However, its printing efficiency is low, the equipment is expensive, and the precision is low, and the materials suitable for printing are limited, further restricting its industrial application. Micro-laser sintering can achieve a resolution of 15 μm and a surface roughness of 1.5 μm in metal material processing, but this process has low printing efficiency and high cost. Electrohydraulic inkjet printing technology can achieve a laboratory precision of 50 nm, and combined with self-assembly processes, it can achieve 15 nm. The nanometer scale is suitable for printing a wide range of materials. Its forming principle is based on traditional inkjet printing. A high-voltage electric field is applied between the nozzle and the substrate, so that the material generates droplets or jets much smaller than the inner diameter of the nozzle under the action of the electric field force. Then, through a precisely controlled point-line-surface layer-by-layer deposition process, nanoscale functional materials are formed.

[0003] Traditional single-nozzle printing has low efficiency, making it difficult to meet the growing application demands for high-resolution and high-efficiency printing. Multi-nozzle systems, referring to two or more nozzles with coupled electric fields, have become a research hotspot in recent years to improve printing efficiency and achieve multi-material collaborative manufacturing. However, multi-nozzle systems face serious electric field crosstalk problems, severely limiting their printing accuracy and stability. Electric field crosstalk mainly includes two forms: first, the end effect, where the asymmetrical distribution of electric fields among multiple nozzles causes a shift in the electric field intensity at the edge nozzles, resulting in jet deflection; second, the shielding effect, where the electric fields between adjacent nozzles interfere with each other, reducing the local electric field intensity and leading to uneven electric field distribution, thereby increasing the start-up voltage and reducing jet stability.

[0004] Therefore, how to effectively reduce the multiple crosstalk between the electric field and the jet, and how to effectively and controllably adjust the jet are key technical challenges for achieving high-precision, multi-material collaborative printing.

[0005] The information disclosed in this background section is only intended to enhance the understanding of the background technology of this application, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0006] To address the impact of electric field crosstalk on jet deflection during multi-nozzle micro / nano 3D printing and to adjust jet deflection according to actual printing needs, this application proposes a multi-nozzle micro / nano 3D printing device and method based on a second electrode-assisted electric field driven by an electric field.

[0007] In some embodiments of this application, a multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field is provided. The 3D printing device includes: an XY stage, a first power supply, a second power supply, a printing nozzle, a second electrode, a metal adapter, a nozzle holder, a Z-axis stage, and a material storage tank. The printing nozzle, the second electrode, the metal adapter, and the material storage tank constitute an ejection unit. The printing nozzle includes an array of nozzles for extruding printing material. The printing nozzle is connected to the material storage tank via the metal adapter. The first power supply is connected to the metal adapter to provide a first voltage for controlling the ejection process. Second electrodes are provided on both sides of the array nozzles, and the second power supply is connected to the second electrodes on both sides to provide a deflection voltage for the jet. The ejection unit is connected to the Z-axis stage via the nozzle holder and is placed above the printing platform. The voltage of the second electrode is adjustable, and the jet surface carries a positive charge. Under the interaction of the electric field, the deflection of the jet is controlled by adjusting the voltage of the second electrode.

[0008] In some embodiments of this application, the 3D printing apparatus further includes a printing platform and a receiving substrate, wherein the printing platform is placed on an XY stage and the receiving substrate is placed on the printing platform.

[0009] In some embodiments of this application, the metal adapter is connected to the positive terminal of the first power supply; the second electrode is connected to the positive terminal of the second power supply.

[0010] In some embodiments of this application, the height difference between the array nozzle and the second electrode in the vertical direction is 0-2 mm, preferably 0-1 mm.

[0011] In some embodiments of this application, the lower end of the array nozzle is below the plane where the second electrode is located.

[0012] In some embodiments of this application, two second electrodes are symmetrically arranged on both sides of the array nozzle to maintain stable adjustment of the electric field.

[0013] In some embodiments of this application, the nozzle spacing between the array nozzles is 0.5-2 mm, preferably 0.5-1 mm.

[0014] In some embodiments of this application, the distance between the edge of the array nozzle, i.e. the distance in the horizontal direction between the central axis of the nozzle closest to the second electrode and the second electrode, is 0.5 mm to 2 mm.

[0015] In some embodiments of this application, the inner diameter of the array nozzle is 20 micrometers to 1 millimeter.

[0016] In some embodiments of this application, the second electrode is disposed on a downwardly extending protrusion of the printhead, and the second electrode is parallel to the horizontal plane.

[0017] In some embodiments of this application, the 3D printing apparatus further includes a camera, which is fixed to the Z-axis worktable by a camera mounting bracket for real-time monitoring of the printing process.

[0018] In some embodiments of this application, the 3D printing apparatus further includes a pressure regulating valve, the first end of which is connected to compressed air and the second end of which is connected to the material reservoir of the print head, for providing the back pressure required for printing.

[0019] In some embodiments of this application, the 3D printing apparatus further includes an injection pump connected to a storage cylinder for injecting printing raw materials.

[0020] In some embodiments of this application, the receiving substrate is fixed on the printing platform by means of vacuum adsorption or electromagnetic adsorption.

[0021] In some embodiments of this application, the printing head, except for the array nozzles, is made of resin, and the array nozzles are made of glass.

[0022] In some embodiments of this application, the XY stage is driven by a linear motor, a servo motor, or a stepper motor, with a moving speed of 1-600 mm / s and a positioning accuracy of not less than 5μm; the Z-axis stage is driven by a nanometer-level piezoelectric displacement stage or a servo motor displacement stage, with a positioning accuracy of not less than 0.5μm.

[0023] In some embodiments of this application, the array nozzles are arranged in a straight line, triangle, or rhombus.

[0024] In some embodiments of this application, the number of array nozzles is not limited, but is preferably 2-5.

[0025] In other embodiments of this application, a 3D printing method based on in-situ control of jet deflection using a second electrode is provided, employing one of the aforementioned 3D printing devices, specifically including the following steps: Step 1: Prepare the materials for printing; Step 2: Determine the print head parameters: Place the print head above the printing platform, control the printing height between 10μm and 200μm, and set the printing air pressure between 0.1 MPa and 1 MPa; Step 3: Set the voltage of the first and second electrodes for target printing.

[0026] In some embodiments of this application, the printing raw materials are biological materials such as bio-inks and cell culture media; polymeric materials such as polymers and resins; metallic materials such as stainless steel powder and titanium alloys; ceramic materials such as alumina and silicon nitride; and composite materials such as carbon fiber composites and glass fiber composites.

[0027] In some embodiments of this application, when the voltage applied to the second electrode is less than half of the second voltage, the deflection angle of the jet increases compared to when the second electrode is not placed; when the voltage applied to the second electrode is half of the second voltage, the deflection angle of the jet is the same as when the second electrode is not placed; when the voltage of the second electrode is 1.2 to 1.3 times that of the first electrode, the jet remains vertically ejected.

[0028] In some embodiments of this application, as the nozzle extension length increases, the jet gradually deflects outward; as the nozzle spacing increases, the jet gradually deflects inward.

[0029] In some embodiments of this application, as the edge distance increases, the jet gradually deflects outward; as the voltage of the second electrode increases, the jet gradually deflects inward.

[0030] Compared with the prior art, the beneficial effects of this application are: This application controls the jetting process using a first voltage, while the voltage of the second electrode is used to manipulate the deflection of the jet. Because the voltage of the second electrode is adjustable and the jet surface carries a positive charge, the deflection of the conical jet can be precisely controlled by adjusting the voltage under the interaction of electric fields. This also overcomes the jet deflection problem in electric field-driven jetting micro / nano 3D printing (i.e., mutual interference of electric fields between multiple jets). This method effectively solves the jet deflection problems that are unavoidable in existing electrohydrodynamic jetting printing and electric field-driven jetting micro / nano 3D printing due to their printing principles (such as jet crosstalk and Coulomb repulsion).

[0031] Existing multi-nozzle structures are typically laid out in a linear or rectangular pattern. However, when the multi-nozzle structure is asymmetrical, jet control becomes difficult to achieve. The method in this application can design a corresponding second electrode layout based on the specific structure of the nozzle and effectively control it by adjusting the voltage, thereby meeting the needs of various nozzle structures (such as linear, triangular, and rhomboid) during the printing process. Attached Figure Description

[0032] To more clearly illustrate the implementation method of this application or the technical solution in the prior art, the accompanying drawings used in the description of the implementation method or the prior art will be briefly introduced below.

[0033] Figure 1 This is a schematic diagram of a 3D printing device; Figure 2 A schematic diagram illustrating the principle of how the second electrode affects jet deflection; Figure 3 A schematic diagram illustrating multi-nozzle jetting for micro / nano 3D printing driven by an auxiliary electric field of the second electrode; Figure 4 The characteristics obtained through COMSOL simulation experiments show that the jet deflection angle and the difference in electric field intensity between the inner and outer sides of the nozzle (E1-E2) vary with the ratio of the second electrode voltage to the original voltage (V1 / V0). Figure 5 The jet deflection diagram is a simulation of five nozzles; Figure 6 The jet deflection trend with the second electrode voltage under different spacing conditions; Figure 7 The jet deflection trend with the second electrode voltage under different edge distances; Figure 8 The jet deflection trend with the second electrode voltage under different nozzle extension lengths; Figure 9 The pattern of each parameter; Figure 10 This is a schematic diagram of a printhead.

[0034] In the diagram, 1. XY stage; 2. Printing platform; 3. Receiving substrate; 4. High voltage power supply; 5. Printing nozzle; 6. Second electrode; 7. Array nozzle; 8. Metal adapter; 9. Camera; 10. Camera mounting bracket; 11. Nozzle mounting bracket; 12. Z-axis stage; 13. Material storage tank; 14. Pressure regulating valve; 1101. First end; 1102. Second end; 15. Injection pump. Detailed Implementation

[0035] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0036] In some embodiments of this application, amino resin is selected as the printing material, and its properties are shown in Table 1. The multi-nozzle used is made of imported 9400 white resin by photocuring technology, which has excellent strength, hardness and insulation properties.

[0037] Table 1 Material parameters of amino resins parameter Amino resin Manufacturer Guangdong Wengjiang Chemical Reagent Co., Ltd. Chemical formula (C3H6CH20)X Viscosity 23℃ 3200-9800 (mPa·s) density 1.18 (Kg / L) softening point 85℃~100 ℃ In some embodiments of this application, such as Figure 1 As shown, a multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driving is provided. It includes: an XY stage 1 (i.e., a two-dimensional stage), a printing platform 2, a receiving substrate 3 (substrate or base), a high-voltage power supply 4, a printing nozzle 5, a second electrode 6, an array nozzle 7, a metal adapter 8, a camera 9, a camera mounting bracket 10, a nozzle mounting bracket 11, a Z-axis stage 12, a material storage tank 13, a pressure regulating valve 14, and an injection pump 15.

[0038] The high-voltage power supply 4 includes a first power supply and a second power supply. The print head 5, second electrode 6, metal adapter 8, and storage tank 13 form the injection unit. The second electrode 6 is placed on the downward-protruding portion of the print head 5 and connected to the second power supply. The print head 5 includes an array of nozzles 7 and is connected to the storage tank via the metal adapter 8. The first power supply is connected to the metal adapter 8 to provide printing voltage. The printing platform 2 is placed on the XY stage 1. The receiving substrate 3 is placed on the printing platform 2 and fixed to it by vacuum adsorption or electromagnetic adsorption. The injection unit is connected to the Z-axis stage 12 and positioned directly above the printing platform 2. The camera 9 is fixed to the Z-axis stage 12 via a camera mounting bracket 10. The pressure regulating valve 14 has its first end 1101 connected to compressed air and its second end 1102 connected to the storage tank 13 of the print head. The injection pump 15 is connected to the storage tank 13 of the print head.

[0039] In some embodiments of this application, the XY stage 1 adopts a high-speed and high-precision displacement stage, and linear motor drive, servo motor drive, and high-precision stepper motor drive are preferred. The XY stage has a moving speed of 1-600 mm / s and a repeatability of not less than 5 μm.

[0040] In some embodiments of this application, the Z-axis worktable 12 is a high-precision Z-axis displacement stage, preferably a high-precision nanoscale piezoelectric displacement stage or an ultra-high-precision servo motor displacement stage, with a positioning accuracy of not less than 0.5 μm.

[0041] In some embodiments of this application, the XY stage 1 adopts a high-precision linear slide with a working stroke of 200 mm and a repeatability of not less than 0.4 μm; the Z-axis stage 12 adopts a high-precision nanoscale piezoelectric displacement stage with a positioning accuracy of 0.1 μm.

[0042] In some embodiments of this application, an electric field-driven jet deposition micro / nano 3D printing device is employed, applying a voltage of 4000 V and an air pressure of 0.1 MPa above the nozzle, and printing is performed by gradually adjusting the voltage of the second electrodes on both sides. During this process, the deflection angle of the jet gradually decreases as the voltage of the second electrodes increases.

[0043] Figure 3 For the simulation model, the printing voltage V0 = 10000V and the inlet flow velocity was 0.05 m / s during the simulation. The uniformity and stability of the electric field distribution were evaluated by calculating the difference in electric field intensity (E1-E2) on both sides of the nozzle and combining it with the deflection angle of the jet. The results are as follows: Figure 4As shown, with the gradual increase of the second electrode voltage, the electric field strength on both sides gradually transitions from a state of lower on the left and higher on the right to a balanced distribution, eventually returning to a state of higher on the left and lower on the right. When the electric field strength on both sides of the printing nozzle is the same, the jet will deflect outwards. When the electric field on the outside of the nozzle is slightly greater than that on the inside (the difference is 1.59 × 10⁵ V / m, and the ratio of the second electrode voltage to the first voltage, V1 / V0, is 1.25), the jet is vertically downwards (deflection angle is 0°).

[0044] To further verify the scalability of this process in large-scale array nozzles, it was extended to a five-nozzle structure. The settings for the five-nozzle structure remained consistent with those described earlier (V1 = 10000 V, inlet flow velocity 0.05 m / s, etc.). By adjusting the second electrode voltage V1, the ratio of V1 / V0 was varied within the range of 0.5 to 2. The results are as follows. Figure 5 As shown, with the increase of the V1 / V0 ratio, the jet deflection angle of the outermost nozzle gradually decreases from 14° to -8°, and the jet deflection angle of the inner nozzle gradually decreases from 6° to -3°. Specifically, when V1 / V0 = 1.22, the jet is ejected vertically downwards. This result shows that in the five-nozzle structure, the influence of the second electrode on jet deflection is highly consistent with the cases of two-nozzle and three-nozzle systems, verifying the universality of this process in multi-nozzle arrays.

[0045] To verify the effects of nozzle spacing, edge distance, and nozzle extension length on the jet deflection angle, a single-variable control experiment was conducted with nozzle spacing of 1 mm, edge distance of 1 mm, and extension length of 0.3 mm as the basic parameter set.

[0046] The jet deflection angle (Δ) was adjusted to 0.7 mm, 1 mm, and 1.3 mm. The voltage of the second electrode was gradually increased, and the deflection angle of the jet was measured. Experimental results show that the deflection angle of the jet increases as the jet deflection angle decreases. At a jet deflection angle of 1.3 mm, only 3500 V is needed to effectively suppress jet deflection. Figure 6 As shown.

[0047] The edge distance e was adjusted to 0.5 mm, 1 mm, and 1.5 mm, with the voltage of the second electrode gradually increased. The results showed that the deflection angle of the jet gradually increased with the increase of the edge distance. When the edge distance was 0.5 mm, only 3000 V was needed to suppress the jet deflection. Figure 7 As shown.

[0048] Finally, the nozzle extension length L was adjusted to 0.1 mm, 0.3 mm, and 0.5 mm, and the voltage of the second electrode was gradually increased. As the nozzle extension length increased, the deflection angle of the jet also gradually increased. When the nozzle extension length was 0.1 mm, applying a voltage of 2000 V was sufficient to suppress the jet deflection. Figure 8 As shown.

[0049] Combining the geometric parameters of the multi-nozzle structure when the jet deflection angle is zero, such as Figure 9 As shown in the figure, analysis reveals that the influence of each factor on the jet deflection angle varies, with the order of influence being: voltage (V1) > nozzle spacing (Δ) > edge distance (e) > nozzle extension length (L). This finding provides important experimental evidence for nozzle design optimization and jet deflection control.

[0050] In some embodiments of this application, the required multi-nozzle device was successfully designed and manufactured. Under the conditions of a printing voltage of 4000 V, a nozzle extension length of 0.3 mm, a spacing of 1 mm, and a margin of 1 mm, deflection-free printing of the jet can be achieved by applying a voltage of 4000 V to the second electrode.

[0051] In some embodiments of this application, a high-speed camera is used to capture the deflection angle of the jet in real time. Combined with image recognition and computer vision technology, features are extracted from the images captured by the camera at the nozzle, thereby classifying and identifying the state of the conical jet and calculating its characteristic parameters for real-time monitoring. Based on the extracted feature information, the system will control the voltage of the second electrode in real time to suppress jet deflection.

[0052] This application introduces a second electrode to generate an adjustable electric field, thereby optimizing the electric field distribution around the printhead and reducing the Coulomb interaction effect in multi-nozzle systems. Specifically, traditional multi-nozzle electric field jetting systems are often affected by the coupling electric field between printheads, causing jet trajectory deviation and reducing printing accuracy. This application, however, applies an adjustable voltage to enable the second auxiliary electrode to generate a compensating electric field, offsetting or reducing electric field crosstalk between printheads, thus maintaining the stability and directionality of the jet.

[0053] Furthermore, this application can dynamically adjust the voltage of the auxiliary electrode according to the changes in the electric field during the jetting process, thereby achieving precise jet guidance control, improving the printing accuracy and stability of the multi-nozzle system, and thus significantly improving the processing quality and consistency of micro-nano 3D printing.

[0054] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven by an electric field, characterized in that, The 3D printing device includes: an XY stage, a printing platform, a receiving substrate, a first power supply, a second power supply, a printing nozzle, a second electrode, a metal adapter, a nozzle holder, a Z-axis stage, and a material storage tank; wherein the printing nozzle, the second electrode, the metal adapter, and the material storage tank constitute an ejection unit; wherein the printing nozzle includes an array of nozzles for extruding printing material, the printing nozzle is connected to the material storage tank via the metal adapter, the first power supply is connected to the metal adapter to provide a first voltage for controlling the ejection process; second electrodes are provided on both sides of the array nozzles, and the second power supply is connected to the second electrodes on both sides to provide a deflection voltage for the jet; the printing platform is placed on the XY stage, and the receiving substrate is placed on the printing platform; the ejection unit is connected to the Z-axis stage via the nozzle holder and is placed above the printing platform; the voltage of the second electrode is adjustable, and the jet surface carries a positive charge, and the deflection of the jet is controlled by adjusting the voltage of the second electrode under the interaction of the electric field.

2. The multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven according to claim 1, characterized in that, The metal adapter is connected to the positive terminal of the first power source; the second electrode is connected to the positive terminal of the second power source.

3. The multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven according to claim 1, characterized in that, The vertical height difference between the array nozzle and the second electrode is 0-2 mm, preferably 0-1 mm; the lower end of the array nozzle is lower than the plane where the second electrode is located; the nozzle spacing between the array nozzles is 0.5-2 mm, preferably 0.5-1 mm; the edge distance, that is, the distance between the nozzle closest to the second electrode and the second electrode in the horizontal direction, is 0.5 mm to 2 mm.

4. The multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven according to claim 1, characterized in that, The second electrode is disposed on the downward-extending protrusion of the print head; the second electrode is parallel to the horizontal plane.

5. The multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven according to claim 1, characterized in that, The 3D printing device also includes a camera, which is fixed to the Z-axis worktable by a camera mounting bracket for real-time monitoring of the printing process.

6. The multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven according to claim 1, characterized in that, The 3D printing device also includes a pressure regulating valve, the first end of which is connected to compressed air and the second end of which is connected to the material storage cylinder of the printing nozzle, for providing the back pressure required for the extrusion of printing material; the 3D printing device also includes an injection pump, which is connected to the material storage cylinder, for injecting printing material.

7. The multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven according to claim 1, characterized in that, The receiving substrate is fixed on the printing platform by vacuum adsorption or electromagnetic adsorption; the printing nozzle, except for the array nozzle, is made of resin, and the array nozzle is made of glass.

8. The multi-nozzle micro / nano 3D printing device based on a second electrode-assisted electric field driven according to claim 1, characterized in that, The XY stage is driven by a linear motor, servo motor, or stepper motor, with a moving speed of 1-600 mm / s and a positioning accuracy of no less than 5μm. The Z-axis stage is driven by a nanometer-level piezoelectric displacement stage or a servo motor displacement stage, with a positioning accuracy of no less than 0.5μm.

9. A method for multi-nozzle micro / nano 3D printing based on a second electrode-assisted electric field driven method, using the 3D printing equipment according to any one of claims 1-8, characterized in that, Specifically, the following steps are included: Step 1: Prepare the materials for printing; Step 2: Determine the print head parameters: Place the print head above the printing platform, control the printing height between 10μm and 200μm, and set the printing air pressure between 0.1 MPa and 1 MPa; Step 3: Set the voltage of the first and second electrodes for target printing.

10. A 3D printing method based on in-situ jet deflection control using a second electrode according to claim 9, characterized in that, When the voltage applied to the second electrode is less than half of the second voltage, the deflection angle of the jet increases compared to when the second electrode is not placed; when the voltage applied to the second electrode is half of the second voltage, the deflection angle of the jet is the same as when the second electrode is not placed; when the voltage of the second electrode is 1.2 to 1.3 times that of the first electrode, the jet remains perpendicular; as the nozzle extension length increases, the jet gradually deflects outward; as the nozzle spacing increases, the jet gradually deflects inward; as the edge distance increases, the jet gradually deflects outward; as the voltage of the second electrode increases, the jet gradually deflects inward.

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